Generator attachment



Oct. 7, 1947. QRBROWN 2,428,548

GENERATOR ATTACHMENT Fil ed Aug. 51, 1945 WITNESSES: INVENTOR ATTORNEY Patented Oct. 7, 1947 GENERATOR ATTACHMENT Charles R. Brown, Norwood, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 31, 1945, Serial No. 613,763

3 Claims. 1

My invention relates to portable electric generators or the like apparatus which are to be driven from a rotating shaft or machine element for measuring, indicating, testing, balancing and the like purposes, and aims at providing such apparatus with coupling means that are capable of frictionally starting the apparatus and maintaining it in a fixed phase position to the driving rotor once the apparatus has accelerated up to or near the speed of the rotor.

For instance, in known equipment for balancing rotating machine elements, a tachometric type generator is mechanically connected with the rotor in order to generate a sine wave voltage which serves as a time reference for unbalance vibrations determined by vibration pickups.

wave generator, or an attachment for such a generator, which can be operated in the manner of the known hand tachometers but which nevertheless secures a fixed phase relation between generator and rotor once the generator is brought up to speed.

According to the invention, I provide the sine wave generator or the like portable apparatus with a coupling device which has a, housing or main structure firmly attached to the shaft of the generator or apparatus to be driven. A spindle is mounted in the structure so that it extends in the axial direction of the shaft. The spindle is displaceable relative to the structure in the axial direction and is biased by spring means for motion away from the shaft to be driven. A friction prod is mounted at the end of the spindle remote from the shaft and serves to engage the rotor from which the generator or main structure of the coupling device is to be driven. A portion or member, which projects from the structure at the side of the friction prod, serves to establish a positive driving engagement but enters into operation only after the generator and coupling assembly has been forced against the driving rotor in opposition to the spring and by a suflicient extent to secure a frictional starting of the assembly.

These features of my invention and the opera tion of the device will be more fully understood from the following description of the embodiment exemplified by the drawing, in which:

Figure 1 is a part sectional view of the complete generator and coupling unit and shows also part of the rotor from which the generator rotation is to be derived;

Fig. 2 is a radial cross section through the coupling device proper along a plane denoted in Fig. 1 by the dot and dash line marked II--II; and

Fig. 3 is an axial view of the generator and coupling unit.

According to the drawing, a sine wave generator l of the portable type whose output cable is denoted by 2 has its shaft 3 attached to a coupling device. This device has a structure 4 which forms a housing and extends into a sleeve portion 5. The sleeve portion engages the generator shaft 3 and is fastened thereto by means of a cross pin 6. A spindle I is journalled in sleeve bearings 8 and 9 of the structure 4. The spindle 1 extends coaxially with the generator shaft 3 and is axially slidable in the bearings 8 and 9. The hub portion IQ of a driver II is rigidly attached to the spindle I. The driver II is engageable with a stop I2 which forms part of the structure 4 or i rigidly attached thereto. A compression spring I3 is arranged in the structure 4 and abuts against the structure and against the driver I I so as to bias the spindle I for axial motion away from the generator shaft 3. A friction prod I4 of conical shape consisting, for instance, of rubber is mounted on the exterior end of spindle I.

The rotor to be balanced is shown at I6. Its center is determined by a lathe center hole. The rotor has some projection, like the illustrated pin I'I, located eccentrically with respect to the cener hole.

The stop I2 is of limited axial extent. Consequently the driver II is in coupling engagement with stop I2 only as long as the spindle I is not forced into the housing structure 4 beyond the extent of the axial stop and driver engagement.

When performing a balancing method, serving to test the rotor I6 for unbalance and. for eliminating such unbalance, the sine wave generator I is manually held against the rotor I6, so that the prod I4 engages the lathe center hole as shown in Fig. 1. The revolution of rotor I6 is then frictionally imparted. to the prod I4, so that the driver II abuts against the stop I2 and. entrains the structure 4 and hence the shaft 3 or nearly up to the speed of the driving roto'r."

During the accelerating period the pins l and I! rotate relative to each other, but they are at first not in engagement with each other and hence do not interfere with the above described'per formance. A further compression of the spring l3 causes the driver ll to slip off the stop 12,

While now the pins l5 and I! enter into engagement with each other; From this moment on;

the rotor it, by its pin I7, is directly coupled with the structure t and the'shaft 3 so that the coupling is no longer frictional-but involves a 'positive transmission of motion, thereby securing a fixed phase position of the generator relative to the rotor 56 as is necessary fora proper correlation of the generated sine wave voltage to the impulses supplied by the vibration pickups (not illustrated).

For operating speedsup to about 4000 rotations' per minute, the coupling device does not necessarily have to be balanced in order to afford a satisfactory performance; at higher speeds it is preferable to give the device a dynamically balanced design in order to avoid the occurrence of disturbing vibrations.

It will be understood from the foregoing that "it is one of the essential features of my invention to provide a coupling device'for portable generators and the likeoperators which secures 7 further be obvious to those skilled in the art" that the design of units or coupling devices according to the invention permits of various modifications within thes'cope of the invention as set forth in the claims attached hereto.

I claim as my invention:

1. A'coup device for driving the shaft of a portable apparatus from a rotor, comprising a structure having a portion designed for attachment to the shaft in order to impart revolution 'theret'o aspin'dle journalled in said structure coaxially to said portion and being. axially displaceable relative to said structure, 'a prod axially mounted said spindle'at the spindle end remote from said portion so as to be'frictionaliy engageabie with the rotor, spring means for axially biasing said spindle relative to said structure in the direction, toward said prod, a part mounted on Said spindle, said structure'having a stop engageable by said partwherebysaid structure is revolved when said prod is frictionally driven by the rotor, said stop having a limited axial length to become disengaged from said 4 V part when said structure is axially displaceda given extent relative to said spindle in opposition to said spring means, and means projecting from said structure at the side of said prod for positively engaging the rotor in a single predetermined relative angular position after, due to relative axial motion between said structure and said spindle, said stop is disengagedfromsaid part. 2. A coupling device for driving the shaft of a portable apparatus from a rotor comprising a structure, having a portion designed for attachment to the shaft in order to impart revolution thereto, an elongated member arranged in said structure so as to extend coaxially with said portion and being axially displaceable relative to said structure, a friction prod endwise secured to said member at the side remote from said portion so as to be engageable with the rotor, spring means for biasing said member for axial motion relative to said structure in the direction. of said prod; said structure and said memberjbeing engageablewith'each other over aflimitedjr Ii'ge of relative axial displacement sofas toiperii it relative rotation only when they areiax ially displaced a given extent relative to each other'i'n opposition-to said spring means, andmea'ns on said structure at the side of 'said prodfor'posi 'tively" engaging the rotorin a single predeterminedangular position when said structure and said member are-axially' displaced relativeito each other more than said given extent; A

3. reportable apparatusfor balancing and the like measuring and testing purposes, comprising a generator havinga shaft to. -be driven from ja rotor, a revolvable structure having'a'sl'eve ,se-

cured to said shaft fordriving said-shaft, a spindle journalle'd in said structure coaxially with said shaft and being axially displaceable relative thereto, spring means mounted in said structure for biasing saids'pindle away from saidsha ftg a friction prodmount'ed on the end ofsaidspindle remo't'e'from said shaft, said structure andsaid spindle having mutuallyengageabIestop means of limited axial extent so that said spindle "is capable of'revolving said structure unless it is a ially'displaced a given minimum extentrelativ '0 The "followingreferences are i m rtian-rule Y 

